First, congrats on leaving Fanball, you won't regret that decision no matter where you go. Secondly, I would recommend rtsports over mfl. Their pricing is similar, get an early-bird or switching-from-fanball coupon and it'll be $75 or so. They both have every option you are looking for and then some and both provide decent customer service; you won't find that at the espn/cbs/yahoo's of the world. You'll hear lots of opinions on which of rtsports or mfl is better, from people who probably have teams in one or the other but not both. There's one main difference though and that's how the website looks and presents information. What you get with rtsports that I prefer over MFL is an easy-to-use, professional looking website that all your owners can quickly pick up and understand. For a league that is so afraid of change that they'll stay with Fanball for 10 years longer than they should, that is very important. Some prefer the MFL style that lets every owner pick their own colors and skins and menus, etc. But even after being on their site for years I find it's presentation to be convoluted and hard to follow. For me, that would tip the scales in rtsports' favor for a league like yours.
Just my 2 cents.